Air blower

ABSTRACT

An air blower capable of suppressing movement of an impeller in a thrust direction is provided. A first case includes a first air inlet and a first air outlet. A second case includes a second air inlet communicating with the first air inlet and a second air outlet communicating with the first air outlet. An impeller is provided inside the second case. A motor rotates the impeller. A first flow channel is provided between the motor and the second case on the opposite side of the first air inlet and the second air inlet relatively to the impeller. A second flow channel is provided between the first case and the second case and communicates with the first flow channel, the first air inlet, and the second air inlet.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No. PCT/JP2021/005253, filed on Feb. 12, 2021, which claims priority to and the benefit of Japanese Patent Application No. 2020-054420, filed on Mar. 25, 2020 and Japanese Patent Application No. 2020-054421, filed on Mar. 25, 2020. The disclosures of the above applications are incorporated herein by reference.

FIELD

The present disclosure relates to an air blower using, for example, a centrifugal fan.

BACKGROUND

An air blower using, for example, a centrifugal fan comprises an impeller, motor configured to rotate the impeller, air inlet provided in the rotational axis direction of the impeller, and air outlet arranged in a direction perpendicular to the air inlet. When the impeller is rotated by the motor, a pressure difference is created between the top surface side (air inlet side) and undersurface side relative to the rotational axis direction of the impeller, whereby the motor shaft and impeller are moved in the thrust direction (rotational axis direction) and impeller is brought into contact with the housing of the air blower.

A technique of eliminating a pressure difference between the top surface and undersurface of the impeller by providing a pressure chamber and valve chamber adjacent to the pressure chamber on each of the top surface and undersurface of the impeller is developed (see, for example, Patent Literature 1 (JP 2006-129638 A)).

Further, there is a technique of equalizing the pressures at the top surface and undersurface of the impeller by providing a plurality of ring-shaped blade retainer plates on each of the top surface and undersurface of the impeller and discharging the air sucked from the air inlet from the air outlet (see, for example, Patent Literature 2 (JP 4716750 B)).

SUMMARY

An embodiment described herein aims to provide an air blower capable of suppressing movement of an impeller thereof in the thrust direction.

An air blower of this embodiment includes a first case including a first air inlet and a first air outlet, a second case provided inside the first case and including a second air inlet communicating with the first air inlet and a second air outlet communicating with the first air outlet, an impeller being provided inside the second case, a rotational axis of which is made coincident with a central axis of each of the first air inlet and the second air inlet, and serving as a centrifugal fan, a motor being provided inside the second case and to rotate the impeller, a first flow channel provided between the motor and the second case on the opposite side of the first air inlet of the impeller and the second air inlet, and a second flow channel provided between the first case and the second case and communicating with the first flow channel, the first air inlet, and the second air inlet.

Additional objects and advantages of the disclosure will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the disclosure. The objects and advantages of the disclosure may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.

DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the disclosure, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the disclosure.

FIG. 1 is a top view showing an air blower according to an embodiment of the present disclosure.

FIG. 2 is a cross-sectional view along line II-II of FIG. 1 .

FIG. 3 is a perspective exploded view showing a part of FIG. 1 .

FIG. 4 is a perspective view showing another part of FIG. 1 .

FIG. 5 is a view showing a function of FIG. 1 and is a cross-sectional view along line V-V of FIG. 1 .

FIG. 6 is a cross-sectional view showing a part A of FIG. 5 in an enlarged form.

DETAILED DESCRIPTION

Embodiments of the present disclosure will be described below with reference to the accompanying drawings. In the drawings, parts identical to each other are denoted by identical reference symbols.

FIG. 1 shows an air blower 10 according to this embodiment. The air blower 10 comprises a top case 11 serving as a housing, and top case 11 has an approximately cylindrical shape and includes an air inlet (first air inlet) 11 a and air outlet (first air outlet) 11 b. The air inlet 11 a is arranged on a top surface of the top case 11 and at a central part thereof, and air outlet 11 b is arranged on a side surface of the top case 11 and in a direction approximately perpendicular to the air inlet 11 a.

As shown in FIG. 2 , inside the top case 11, an inner case 12 is provided. The inner case 12 is divided into a first inner case 12-1 on the lower side and second inner case 12-2 on the upper side. However, the inner case 12 is not necessarily divided, and may be integrally configured. The inner case 12 includes an air inlet (second air inlet) 12 a communicating with the air inlet 11 a of the top case 11 and air outlet (second air outlet) 12 b communicating with the air outlet 11 b of the top case 11.

The inner diameter of the air inlet 12 a of the inner case 12 is greater than the inner diameter of the air inlet 11 a of the top case 11, and air inlet 11 a is arranged inside the air inlet 12 a. Accordingly, the air inlet 11 a and air inlet 12 a are arranged concentric with each other.

Furthermore, between the inner case 12 and top case 11, a flow channel (first flow channel) (CH3) to be described later is provided. That is, a part of the inner case 12 is separate from an inner surface of the top case 11 and the flow channel (CH3) is formed at this part.

To a lower part of each of the top case 11 and inner case 12, a base 13 is attached by a plurality of screws 14. Between the lower part of each of the top case 11 and inner case 12 and base 13, a base plate 15 is provided. The base plate 15 is fixed to the base 13 by a plurality of screws 16.

Between a circumference of the base plate 15 and top case 11, a ring-shaped gasket 18 serving as a sealing member is provided and, also between the circumference of the base plate 15 and base 13, a ring-shaped gasket 19 serving as a sealing member is provided. The gaskets 18 and 19 are each constituted of an elastic body such as rubber. A gap between the top case 11 and base plate 15 is blocked by the gasket 18 and, gap between the base 13 and base plate 15 is blocked by the gasket 19. Accordingly, the top case 11 and base 13 are sealed up and air is prevented from leaking out of the top case 11 and base 13.

As shown in FIG. 2 and FIG. 3 , an opening portion 15 a is provided at a central part of the base plate 15 and a stator 17 a of a motor 17 is arranged inside the opening portion 15 a. The stator 17 a is cylindrical and is accommodated in a concave portion 13 a provided at a central part of the base 13.

An inner diameter of the opening portion 15 a of the base plate 15 is equal to or slightly greater than an outer diameter of the stator 17 a and a plurality of concave portions 15 b is provided in an inner circumference of the opening portion 15 a. Accordingly, a plurality of gaps is formed between the base plate 15 and stator 17 a by the plurality of concave portions 15 b.

Furthermore, a plurality of opening portions 15 c is provided in a circumferential part of the base plate 15. These opening portions 15 c are positioned outside the inner case 12 and inside the top case 11 and are arranged in a one-to-one correspondence with a plurality of concave portions 13 b provided on the base 13.

The concave portions 13 b of the base 13, concave portions 15 b of the base plate 15, and opening portions 15 c constitute a flow channel (CH2) communicating with the aforementioned flow channel (CH3) between the inner case 12 and top case 11.

The motor 17 is arranged inside the inner case 12, more specifically, the motor 17 is arranged inside the first inner case 12-1. The motor 17 includes the aforementioned stator 17 a, sleeve 17 b, shaft 17 c, bearing 17 d, a plurality of coils 17 e, a plurality of yokes 17 f, rotor holder 17 g, permanent magnet 17 h, and shaft holder 17 i.

The sleeve 17 b is provided inside the stator 17 a and shaft 17 c is arranged inside the sleeve 17 b. The fixed portion of the bearing 17 d is fixed to the inside of the sleeve 17 b and rotating portion of the bearing 17 d is fixed to a first end of the shaft 17 c. The shaft 17 c retained by the bearing 17 d inside the sleeve 17 and is retained in the thrust direction by the magnetic force. The sleeve 17 b and shaft 17 c may constitute an aerodynamic pressure bearing. The plurality of yokes 17 f around which the plurality of coils 17 e is each wound are arranged around the stator 17 a. The shaft holder 17 i is fixed to a second end of the shaft 17 c, and rotor holder 17 g is retained inside the shaft holder 17 i. The permanent magnet 17 h is cylindrical and is fixed to the inside of the rotor holder 17 g. An inner surface of the permanent magnet 17 h is arranged separate from the plurality of yokes 17 f.

An outer surface of the shaft holder 17 i is separated from an inner surface of the first inner case 12-1, and a gap formed between the outer surface of the shaft holder 17 i and first inner case 12-1 constitute a flow channel (CH1).

It should be noted that the configuration of the motor 17 is not limited to the above and can be modified.

An impeller 20 is arranged inside the second inner case 12-2 and is attached to an upper part of the shaft holder 17 i.

As shown in FIG. 4 , the impeller 20 is a centrifugal fan and is, for example, a so-called turbofan. However, the impeller 20 is not limited to the turbofan.

The impeller 20 comprises an air inlet (third air inlet) 20 a, a plurality of air outlets (third air outlets) 20 b, and plurality of blades 20 c. The air inlet 20 a is provided at a central part of the top surface (first surface) 20 d of the impeller 20, and plurality of air outlets is arranged along the outer circumference of the impeller 20. The plurality of blades 20 is arranged between the top surface 20 d of the impeller 20 and undersurface (second surface) 20 e thereof and between the air inlet 20 a and plurality of air outlets 20 b.

Furthermore, on the top surface 20 d of the impeller 20 and around the air inlet 20 a, a ring-shaped protruding portion 20 f is provided.

As shown in FIG. 2 , in the impeller 20, in a state where the impeller 20 is arranged inside the second inner case 12-2, the air inlet 20 a thereof is opposed to the air inlet 11 a of the top case 11 and air inlet 12 a of the inner case 12. Each of the top surface 20 d of the impeller 20, undersurface 20 e thereof, and side surface thereof in which the air outlets 20 b are provided is separated from the inner surface of the second inner case 12-2 and a gap is formed therebetween.

Further, on the inner surface of the second inner case 12-2 and around the air inlet 12 a, a ring-shaped concave portion 12 c is provided, and protruding portion 20 f of the impeller 20 is arranged inside the concave portion 12 c. In a state where the protruding portion 20 f is arranged inside the concave portion 12 c, between the protruding portion 20 f and concave portion 12 c, a gap communicating with the gap provided between the top surface 20 d of the impeller 20 and inner surface of the second inner case 12-2 is formed. This gap constitutes a flow channel (second flow channel) (CH4). The gap formed by the concave portion 12 c and protruding portion 20 f is made to communicate with the air inlet 11 a of the top case 11 and air inlet 12 a of the inner case 12.

More specifically, the inner surface of the air inlet 11 a of the top case 11, inner surface of the air inlet 12 a of the inner case 12, and ring-shaped gap between the protruding portion 20 f of the impeller 20 and concave portion 12 c of the second inner case 12-2 are parallel to each other. Accordingly, the direction of air flowing out of the ring-shaped flow channel is parallel to the direction of air flowing into each of the air inlet 11 a of the top case 11 and air inlet 12 a of the second inner case 12-2.

Further, the gap between the top surface 20 d of the impeller 20 and second inner case 12-2 is greater than the ring-shaped gap (gap in the radial direction (direction perpendicular to the rotational axis)) between the protruding portion 20 f of the impeller 20 and concave portion 12 c of the second inner case 12-2, and functions as a valve chamber configured to control the flow of air. Between the undersurface 20 e of the impeller 20 and second inner case 12-2 too, a gap (a part of the flow channel CH3) similar to that on the top surface 20 d side of the impeller 20 is provided, and the pressure on the top surface 20 d of the impeller 20 and pressure on the undersurface 20 e thereof are equally maintained by the gap on the top surface 20 d side of the impeller 20 and gap on the undersurface 20 e side thereof. Accordingly, movement of the impeller 20 in the thrust direction is suppressed.

The ring-shaped gap between the protruding portion 20 f of the impeller 20 and concave portion 12 c of the second inner case 12-2 is less than the gap between the top surface 20 d of the impeller 20 and second inner case 12-2 and functions as a choke (second choke) 21 configured to narrow the flow of air.

Further, the ring-shaped gap between the inner surface of the air inlet 12 a of the second inner case 12-2 and outer surface of the air inlet 11 a of the top case 11 is less than the gap between the undersurface 20 e of the impeller 20 and second inner case 12-2 or gap between the top case 11 and inner case 12 and functions as a choke (first choke) 22 configured to narrow the flow of air.

In this embodiment, the ring-shaped choke 21 is arranged outside the air inlet 11 a and air inlet 12 a and direction of the flow of air flowing out of the choke 21 is parallel to the direction of the flow of air sucked from the air inlet 11 a and air inlet 12 a. In other words, the choke 21 is arranged in parallel with the inner surface of the air inlet 11 a of the top case 11 and inner surface of the air inlet 12 a of the inner case 12.

The ring-shaped choke 22 is arranged between the air inlet 11 a and air inlet 12 a and direction of the flow of air flowing out of the choke 22 is parallel to the direction of the flow of air flowing out of the air inlet 11 a, air inlet 12 a, and choke 21. That is, the choke 22 is arranged in parallel with the choke 21.

(Function)

The function of the aforementioned air blower 10 will be described below with reference to FIG. 5 and FIG. 6 .

When the motor 17 is driven and impeller 20 is rotated, air introduced from each of the air inlet 11 a of the top case 11 and air inlet 12 a of the inner case 12 is guided to the air inlet 20 a of the impeller 20 and is discharged from the air outlets 20 b of the impeller 20, air outlet 12 b of the inner case 12, and air outlet 11 b of the top case 11.

On the other hand, part of the air inside the inner case 12 is introduced into the air inlet 20 a of the impeller 20 from the part between the air inlet 11 a of the top case 11 and air inlet 12 a of the inner case 12 through the flow channel CH1 between the motor 17 and inner case 12 (first inner case 12-1), flow channel CH2 extending through the opening portion 15 a and concave portions 15 b of the base plate 15, concave portions 13 b of the base 13, and opening portions 15 c of the base plate 15, flow channel CH3 between the top case 11 and inner case 12, and choke 22.

As described above, the air on the lower side of the impeller 20 is guided to the upper side (upper side of the impeller 20) of the inner case 12 through the flow channels CH1, CH2, and CH3 and choke 22 and is introduced into the air inlet 20 a of the impeller 20 together with the air introduced from the air inlet 11 a of the top case 11. Accordingly, it is possible to suppress movement of the impeller 20 in the thrust direction.

Furthermore, part of the air inside the inner case 12 is introduced into the air inlet 20 a of the impeller 20 through the flow channel CH4 between the top surface (first surface) 20 d of the impeller 20 and inner case 12 (second inner case 12-2) and choke 21 together with the air passing through the flow channel CH3 and choke 22 and air introduced from the air inlet 11 a of the top case 11. Moreover, the direction of the air introduced from the choke 21 into the air inlet 20 a of the impeller 20 is made parallel to the direction of the air passing through the choke 22, and direction of the air introduced from the air inlet 11 a of the top case 11. Accordingly, the flow of air introduced from the air inlet 11 a of the top case 11, flow of air from the choke 22, and flow of air from the choke 21 are made to join each other and are introduced into the impeller 20. Accordingly, it is possible to further suppress movement of the impeller 20 in the thrust direction.

Advantageous Effects of Embodiment

According to the embodiment described above, the air blower 10 includes the top case 11 and inner case 12 provided inside the top case 11, further, motor 17 and impeller 20 are arranged inside the inner case 12 and, between the inner case 12 and motor 17 and between the top case 11 and inner case 12, the flow channels CH1, CH2, and CH3 are respectively formed. Accordingly, air leaking from the inner case 12 into the top case 11 is guided to the air inlet 20 a of the impeller 20 from the part between the air inlet 11 a of the top case 11 and air inlet 12 a of the inner case 12 through the flow channels CH1, CH2, and CH3, and choke 22 each provided between the top case 11 and inner case 12. Accordingly, it is possible to suppress movement of the impeller 20 in the thrust direction and prevent the impeller 20 from coming into contact with the inner case 12.

Moreover, the air blower 10 has a double structure constituted of the top case 11 and inner case 12. Accordingly, the flow of air created by the rotation of the impeller 20 is discharged from the air outlet 11 b of the top case 11, and it is possible to prevent air from leaking out of the other portions of the top case 11.

Further, according to the embodiment described above, the inner case 12 includes a ring-shaped concave portion 12 c around the air inlet 12 a, impeller 20 includes, around the air inlet 20 a thereof, the ring-shaped protruding portion 20 f to be arranged inside the concave portion 12 c, and ring-shaped choke 21 is formed around the air inlet 11 a and air inlet 12 a by the concave portion 12 c and protruding portion 20 f. Moreover, the direction of air introduced from the choke 21 into the air inlet 20 a of the impeller 20 is made parallel to the direction of the air passing through the choke 22 between the top case 11 and inner case 12 and direction of the air introduced from the air inlet 11 a of the top case 11. Accordingly, the flow of air introduced from the air inlet 11 a of the top case 11, flow of air from the choke 22, and flow of air from the choke 21 are made to join each other and are introduced into the impeller 20. Accordingly, it is possible to further suppress movement of the impeller 20 in the thrust direction, and prevent the impeller 20 from coming into contact with the inner case 12.

Furthermore, the direction of the choke 21 is parallel to the choke 22, inner circumferential surface of the air inlet 11 a, and inner circumferential surface of the air inlet 12 a. Accordingly, even if the impeller 20 is moved in the thrust direction, the width of the gap between the concave portion 12 c and protruding portion 20 f each constituting the choke 21 is never changed in the direction intersecting the rotational axis. Accordingly, when the rotational speed of the impeller 20 is constant, it is possible to maintain the quantity of air (flow rate of air) to be introduced from the choke 21 into the air inlet 20 a constant, stably suppress movement of the impeller 20 in the thrust direction, and facilitate management of the dimension of the choke 21.

The choke 22 is formed by arranging the air inlet 12 a of the second inner case 12-2 concentric with the air inlet 11 a of the top case 11. Accordingly, regarding the choke 22, as in the case of the choke 21, even when the second inner case 12-2 (inner case 12) is arranged out of alignment in the thrust direction relatively to the top case 11, the width of the choke 22 is never changed in the direction intersecting the rotational axis. Accordingly, it is possible to facilitate management of the dimension of the choke 22.

Further, the direction of the air introduced from each of the choke 21 and choke 22 into the air inlet 20 a of the impeller 20 is made parallel to the direction of the air introduced from the air inlet 11 a of the top case 11. Accordingly, the loss in the flow rate is smaller in comparison with the case where the choke 21 and choke 22 are arranged in the direction (radial direction) perpendicular to the air inlet 11 a of the top case 11 and, furthermore, it is possible to reduce the noise.

More specifically, the air introduced from the air inlet 11 a of the top case 11 into the air inlet 20 a of the impeller 20 gradually changes the direction thereof at a right angle toward the air outlets 20 b. Therefore, the flow of air from the choke 22 closer to the air inlet 20 a than the choke 21 joins the flow of air introduced from the air inlet 20 a more smoothly as compared with the flow of air from the choke 21, and thus the loss in the flow rate and noise are reduced.

Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the disclosure in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. 

What is claimed is:
 1. An air blower comprising: a first case including a first air inlet and a first air outlet; a second case provided inside the first case and including a second air inlet communicating with the first air inlet and a second air outlet communicating with the first air outlet; an impeller being provided inside the second case, a rotational axis of which is made coincident with a central axis of each of the first air inlet and the second air inlet, and serving as a centrifugal fan; a motor being provided inside the second case and to rotate the impeller; a first flow channel provided between the motor and the second case on the opposite side of the first air inlet of the impeller and the second air inlet; and a second flow channel provided between the first case and the second case and communicating with the first flow channel, the first air inlet, and the second air inlet.
 2. The air blower of claim 1, wherein the first air inlet of the first case includes a first side surface parallel to the central axis, and the second air inlet of the second case includes a second side surface parallel to the first side surface.
 3. The air blower of claim 2, further comprising a second flow channel provided between a first surface of the impeller on the first and second air inlets side and a second surface of the second case opposed to the first surface, and between the second air inlet of the second case and a surface of the impeller opposed to the second air inlet, and communicating with the first air inlet and the second air inlet.
 4. The air blower of claim 3, further comprising: a base configured to cover a bottom portion of the first case; and a ring-shaped sealing member provided between the first case and the base.
 5. An air blower comprising: a first case including a first air inlet and a first air outlet; a second case provided inside the first case and including a second air inlet communicating with the first air inlet and a second air outlet communicating with the first air outlet; an impeller being provided inside the second case, a rotational axis of which is made coincident with a central axis of each of the first air inlet and the second air inlet, and serving as a centrifugal fan; and a motor being provided inside the second case and configured to rotate the impeller, wherein the first air inlet and the second air inlet are arranged concentric with each other, and two side surfaces between the first air inlet and the second air inlet are parallel to the rotational axis and each form a first flow channel which guides air between the first case and the second case to the first air inlet and the second air inlet.
 6. The air blower of claim 5, wherein the second case includes a ring-shaped concave portion provided around the second air inlet and in a surface thereof opposed to the impeller, the impeller includes a ring-shaped protruding portion on the first surface thereof on the first and second air inlets side, the ring-shaped protruding portion being arranged inside the concave portion, and two side surfaces between the concave portion and the protruding portion and parallel to the rotational axis each constitute a second flow channel which guides air on the surface corresponding to the first air inlet and the second air inlet of the impeller to the first air outlet and the second air outlet.
 7. The air blower of claim 6, wherein a gap of the first flow channel in a direction intersecting the rotational axis at right angles is less than a gap between the first case and the second case, and forms a first choke.
 8. The air blower of claim 7, wherein a gap of the second flow channel in a direction intersecting the rotational axis at right angles is less than a gap between the surface of the impeller corresponding to the first air inlet and the second air inlet and the second case, and forms a second choke. 